This invention relates generally to semiconductors, and more particularly to a method for determining endpoints in a chemical/mechanical process.
The demand for smaller, more compact consumer electronics has created a need to manufacture complex integrated circuits (ICs) having a large number of transistors packed into smaller and smaller areas. This IC miniaturization trend has led to IC designs having increasingly greater device densities. Device densities for conventional ICs are approximately 8 million transistors per square centimeter and will likely exceed 80 million by the year 2012, for example. Device densities of this magnitude require multiple layer IC designs that utilize multiple levels of metal interconnect and dielectric layers.
Dielectric layers are used between component layers to electrically insulate devices from other layers. Multiple level interconnects are typically used within the dielectric layers to provide communication between device elements within a single layer and between devices residing on different layers. ICs having up to six levels of interconnects for complex logic chips are currently in production, and the use of nine layers or more is anticipated. ICs with small compact dimensions pose many manufacturing challenges.
The present invention achieves technical advantages as a fast, automatic and accurate endpoint detection device and method. A carrier current signal of a motor arm driving a rotating polishing carrier is analyzed to determine significant statistical characteristic changes, in particular, the ratio of standard deviation and mean value of the carrier current signal. When a threshold value is exceeded, an endpoint is detected.
Advantages of the invention include providing a real time endpoint detection with robust algorithms that are effective with a variety of different types of wafers. The invention includes a dynamic feature extraction to minimize human interference and reduce the number of system parameters input. More than one endpoint may be detected for different control targets.